The aim of this study is to evaluate the effect of chemical composition and physical properties of limestone on bulk density, apparent porosity, water absorption rate and P-wave velocity, on the activation energy required for its decomposition process. The activation energy of calcination of spherical particles was calculated from the Arrhenius equation. The samples were calcined by TG-DTA at a temperature range of 25-1000 degrees C and gradient of 10 degrees C/min. Samples with higher % CaCO3 content and P-wave velocity and lower bulk density and porosity show relatively higher activation energy and rate of lime crystallite growth. This is due to the original grain channel pores and the formation of triple junction fractures during calcination, which facilitate transfer of hot gases and diffusivity of the evolved CO2. It is finally concluded that the decomposition of limestone is a temperature, chemical and physical properties dependent process.